1. Field of the Invention
The present invention relates to an inkjet head for an office and industrial use.
2. Related Art
FIG. 1 is a cross-sectional view of a conventional inkjet head 200. As shown in FIG. 1, the inkjet head 200 includes an orifice plate 2, a chamber plate 4, a restrictor plate 6, a diaphragm plate 9, a support plate 17, and a housing 11, which are all fixed one on the other in this order by adhesive. The inkjet head 200 further includes a plurality of laminated-type piezoelectric elements 12 and a fixing plate 13 for supporting the piezoelectric elements 12.
As shown in FIGS. 1 to 3, the orifice plate 2 is formed with a plurality of nozzles 1 through which ink droplets are ejected. The chamber plate 4 is formed with a plurality of pressure chambers 3 in fluid communication with the corresponding nozzles 1. The restrictor plate 6 is formed with a plurality of restrictors 5 that regulate ink flow toward the pressure chambers 3. The diaphragm plate 9 is integrally formed with a filter 8. The support plate 17 is formed with a plurality of through holes 10A and 10B larger than a cross-sectional dimension of the piezoelectric element 12.
The housing 11 is formed with a common ink chamber 16 and an opening 18. The common ink chamber 16 is in fluid communication with all the restrictors 5 via the through holes 10B and the filter 8. The opening 18 is greater than a cross-sectional dimension of the fixing plate 13. A pair of positioning holes 14 are formed through all the orifice plate 2, the chamber plate 4, the restrictor plate 6, the diaphragm plate 9, the support plate 17, and the housing 11 for positioning these members when manufacturing the inkjet head 200. Adhesive agent or the like (not shown) is filled in the positioning holes 14 to fix the members.
As shown in FIG. 2, portions of the diaphragm plate 9 corresponding to the through holes 10A formed in the support plate 17 serve as diaphragms 7. Each piezoelectric element 12 is attached to the corresponding diaphragm 7 through the through hole 10A such that the piezoelectric element 12 confronts the pressure chamber 3 via the diaphragm 7.
In this configuration, ink inside the common ink chamber 16 is distributed to the restrictors 5 and supplied into the pressure chambers 3. Upon application of a driving voltage, the piezoelectric element 12 causes displacement in the diaphragm 7, which in turn decreases the volume of the corresponding pressure chamber 3 with a resultant increase in the internal pressure thereof. This internal pressure ejects ink inside the pressure chamber 3 as an ink droplet through the nozzle 1.
However, in the above configuration, when the inkjet head 200 is produced by adhering all the plates 2, 4, 6, 9, 17 at the same time, and adhered portion 9e of the diaphragm plate 9 (FIG. 4) is not securely adhered to the support plate 17 for the reason that a uniform pressing force is not applied to the adhered portion 9e in a direction indicated by an arrow in FIG. 4 due to the restrictor 5 located adjacent to the adhered portion 9e. Accordingly, there is a danger that the diaphragm plate 9 is adhered to, for example, only a region between points P2 and P3 of the support plate 17, although the diaphragm plate 9 must be adhered to a region between points P1 and P3. This changes a fixed end of the diaphragm from the original point P1 to the point P2, changing the dimension of the diaphragm 7. Unevenness in the position of the fixed ends of the diaphragms 7 varies the deforming amount of the diaphragms 7, and changes ink ejection performance of the nozzles 1, whereby overall ink ejection performance of the inkjet head 200 is degraded.
Further, if adhesion between the adhered portion 9e and the support plate 17 is insecure, when the piezoelectric element 12 deforms the diaphragm 7 in response to a driving voltage, the adhered portion 9e will be easily peeled off the support plate 17, further shifting the fixed end of the diaphragm 7 over a long time use.
It is an object of the present invention to overcome the above problems, and to provide an inkjet head realizing a uniform ink ejection performance.
In order to overcome the above and other object, there is provided an inkjet head including a diaphragm plate having a first surface and a second surface, a piezoelectric element attached to the first surface of the diaphragm plate for selectively deforming the diaphragm plate, a support plate attached to the second surface of the diaphragm plate and formed a first through hole and a second through hole, and a channel plate attached to the support plate in a manner that the support plate is interposed between the channel plate and the diaphragm plate, the channel plate being formed with a channel fluidly connecting the first through hole and the second through hole.
There is also provided an inkjet head including a pair of support plates formed with a through hole, a diaphragm plate interposed between and attached to the pair of support plates, and a piezoelectric element attached to the diaphragm through the through hole formed in one of the support plates. The support plates are substantially identical.
Further, there is provided an inkjet head including a support plate, a diaphragm plate, and a piezoelectric element. The support plate is formed with a through hole. The diaphragm plate is attached to the support plate. A portion of the diaphragm plate corresponding to the through hole serves as a diaphragm. The diaphragm has a first surface confronting the through hole and a second surface opposite to the first surface. The piezoelectric element is attached to the second surface of the diaphragm for selectively deforming the diaphragm.